const fp = require('lodash/fp');

class Maybe {
  static of (value) {
    return new Maybe(value);
  }

  constructor (value) {
    this._value = value;
  }

  map (fn) {
    return !this.isNothing() ? this : Maybe.of(fn(this._value)); // 先判断，如果为null，直接传递，如果不为null则执行fn
  }

  isNothing () {
    return !!this._value;
  }

}


class Container {
  static of (value) {
    return new Container(value);
  }

  constructor (value) {
    this._value = value;
  }

  map (fn) {
    return Container.of(fn(this._value));
  }
}

module.exports = {
  Maybe,
  Container
};